umount.crypt should support lazy unmount (-l option)

[Jani Uusitalo]

umount.crypt doesn't support lazy unmounting:

jani@saegusa:~$ sudo mount .Backup
Password:
jani@saegusa:~$ grep Backup /etc/mtab
/dev/sdc1 /home/jani/.Backup crypt rw,nosuid,nodev,noauto 0 0
jani@saegusa:~$ sudo umount -l .Backup
Unknown option: -l
Usage: umount.crypt [-fnrv] [-?|--help] [--usage]
Unknown option: -l
Usage: umount.crypt [-fnrv] [-?|--help] [--usage]

The usefulness of -l is documented in umount(8).

Strangely, the Debian BTS claims this feature has already been implemented ages ago [1].

*[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=370526

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: libpam-mount 2.10-2build1
ProcVersionSignature: Ubuntu 3.5.0-27.46~precise1-generic 3.5.7.7
Uname: Linux 3.5.0-27-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.1
Architecture: amd64
CheckboxSubmission: 09ae689090491ca53449589269e4bfd8
CheckboxSystem: edda5d4f616ca792bf437989cb597002
Date: Thu Apr 4 22:23:03 2013
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
MarkForUpload: True
SourcePackage: libpam-mount
UpgradeStatus: Upgraded to precise on 2011-11-21 (500 days ago)
modified.conffile..etc.security.pam.mount.conf.xml: [modified]
mtime.conffile..etc.security.pam.mount.conf.xml: 2012-04-29T22:06:40